Peptide The amino group of one amino acid and the carboxyl group of another amino acid can be condensed into a peptide, and the amide group formed is called peptide bond in protein chemistry. The molecule of amino acid is the smallest, and that of protein is the largest. Two or more amino acids are dehydrated and condensed to form several peptide bonds to form a peptide, and multiple peptides are folded in multiple stages to form a protein molecule. Protein is sometimes called a "polypeptide". Dipeptide is a protein fragment composed of two amino acids.

It is mainly divided into medical polypeptide drugs, peptide antibiotics, vaccines, agricultural antibacterial peptides, feed small peptides, daily cosmetics, food soybean peptides, corn peptides, yeast peptides and sea cucumber peptides.

From the functional point of view, it can be divided into antihypertensive peptides, antioxidant peptides, cholesterol-lowering peptides, opioid peptides, high F-value oligopeptides, strong food peptides and so on.

Active peptides are closely related to nutrition, hormones, enzyme inhibition, immune regulation, antibacterial, antiviral and antioxidant activities. Polypeptides are generally divided into: polypeptide drugs and polypeptide health products. Traditional polypeptide drugs are mainly polypeptide hormones. 20 1 1 The development of polypeptide drugs has developed into various fields of disease prevention and treatment, especially the following fields.